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Fix IP adjustment for interpreter EH #117055

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Fix IP adjustment for interpreter EH #117055

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80bca84
Fix IP adjustment for interpreter EH
janvorli Jun 26, 2025
91137ae
Fix build break with interpreter disabled
janvorli Jun 26, 2025
7a5611b
Fix the case when the pEntryFrame is NULL
janvorli Jun 26, 2025
e5df47c
Actually, the check should be for FRAME_TOP, not NULL
janvorli Jun 26, 2025
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6 changes: 6 additions & 0 deletions src/coreclr/vm/excep.cpp
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Expand Up @@ -7360,6 +7360,12 @@ VOID DECLSPEC_NORETURN UnwindAndContinueRethrowHelperAfterCatch(Frame* pEntryFra
}
else
{
#ifdef FEATURE_INTERPRETER
if ((pEntryFrame != FRAME_TOP) && (pEntryFrame->GetFrameIdentifier() == FrameIdentifier::InterpreterFrame))
{
((InterpreterFrame*)pEntryFrame)->SetIsFaulting(true);
}
#endif // FEATURE_INTERPRETER
DispatchManagedException(orThrowable);
}
}
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5 changes: 5 additions & 0 deletions src/coreclr/vm/frames.cpp
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Expand Up @@ -1894,6 +1894,11 @@ void InterpreterFrame::SetContextToInterpMethodContextFrame(T_CONTEXT * pContext
SetSP(pContext, dac_cast<TADDR>(pFrame));
SetFP(pContext, (TADDR)pFrame->pStack);
SetFirstArgReg(pContext, dac_cast<TADDR>(this));
pContext->ContextFlags = CONTEXT_FULL;
if (m_isFaulting)
{
pContext->ContextFlags |= CONTEXT_EXCEPTION_ACTIVE;
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@BrzVlad BrzVlad Jun 27, 2025 •
edited
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How does exactly setting this flag end up preventing the ip adjustment ? Seems not obvious from searching in the code.

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The EH doesn't do adjustment for frames that are marked as faulting. In the JIT/AOT case, these are frames of hardware exceptions where the IP is the IP of the faulting instruction. For the interpreter, the throwing IR opcodes behave the same way. Setting this flag results in setting the m_crawl.isFaulting and m_crawl.isInterrupted to true. The SfiInit and SfiNext perform the IP adjustment only when the isFaulting is not set.
E.g. for the SfiInit, you can see it here:

runtime/src/coreclr/vm/exceptionhandling.cpp

Lines 3863 to 3866 in 50be35a

if (!pThis->m_crawl.HasFaulted() && !pThis->m_crawl.IsIPadjusted())
{
controlPC -= STACKWALK_CONTROLPC_ADJUST_OFFSET;
}

}
}

void InterpreterFrame::UpdateRegDisplay_Impl(const PREGDISPLAY pRD, bool updateFloats)
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11 changes: 10 additions & 1 deletion src/coreclr/vm/frames.h
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Expand Up @@ -2417,7 +2417,8 @@ class InterpreterFrame : public FramedMethodFrame
#ifndef DACCESS_COMPILE
InterpreterFrame(TransitionBlock* pTransitionBlock, InterpMethodContextFrame* pContextFrame)
: FramedMethodFrame(FrameIdentifier::InterpreterFrame, pTransitionBlock, NULL),
m_pTopInterpMethodContextFrame(pContextFrame)
m_pTopInterpMethodContextFrame(pContextFrame),
m_isFaulting(false)
#if defined(HOST_AMD64) && defined(HOST_WINDOWS)
, m_SSP(0)
#endif
Expand Down Expand Up @@ -2471,10 +2472,18 @@ class InterpreterFrame : public FramedMethodFrame
}
#endif // HOST_AMD64 && HOST_WINDOWS

void SetIsFaulting(bool isFaulting)
{
LIMITED_METHOD_CONTRACT;
m_isFaulting = isFaulting;
}

private:
// The last known topmost interpreter frame in the InterpExecMethod belonging to
// this InterpreterFrame.
PTR_InterpMethodContextFrame m_pTopInterpMethodContextFrame;
// Set to true to indicate that the topmost interpreted frame has thrown an exception
bool m_isFaulting;
#if defined(HOST_AMD64) && defined(HOST_WINDOWS)
// Saved SSP of the InterpExecMethod for resuming after catch into interpreter frames.
TADDR m_SSP;
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4 changes: 4 additions & 0 deletions src/coreclr/vm/interpexec.cpp
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Expand Up @@ -1737,12 +1737,14 @@ void InterpExecMethod(InterpreterFrame *pInterpreterFrame, InterpMethodContextFr
{
throwable = LOCAL_VAR(ip[1], OBJECTREF);
}
pInterpreterFrame->SetIsFaulting(true);
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Shouldn't this flag also be set for the other sources of exception throwing in the interp method execution ? Conv ovf opcodes for example

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No, these are all handled in the UnwindAndContinueRethrowHelperAfterCatch

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That one is called in the UNINSTALL_UNWIND_AND_CONTINUE_HANDLER macro in the InterpExecMethod.

DispatchManagedException(throwable);
UNREACHABLE();
break;
}
case INTOP_RETHROW:
{
pInterpreterFrame->SetIsFaulting(true);
DispatchRethrownManagedException();
UNREACHABLE();
break;
Expand Down Expand Up @@ -2220,6 +2222,8 @@ do { \
pMethod = pFrame->startIp->Method;
assert(pMethod->CheckIntegrity());
pThreadContext->pStackPointer = pFrame->pStack + pMethod->allocaSize;

pInterpreterFrame->SetIsFaulting(false);
goto MAIN_LOOP;
}

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6 changes: 5 additions & 1 deletion src/coreclr/vm/stackwalk.cpp
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Expand Up @@ -2860,8 +2860,12 @@ void StackFrameIterator::ProcessCurrentFrame(void)
m_interpExecMethodFirstArgReg = (TADDR)GetFirstArgReg(pRD->pCurrentContext);

((PTR_InterpreterFrame)m_crawl.pFrame)->SetContextToInterpMethodContextFrame(pRD->pCurrentContext);
if (pRD->pCurrentContext->ContextFlags & CONTEXT_EXCEPTION_ACTIVE)
{
m_crawl.isInterrupted = true;
m_crawl.hasFaulted = true;
}

pRD->pCurrentContext->ContextFlags = CONTEXT_FULL;
SyncRegDisplayToCurrentContext(pRD);
ProcessIp(GetControlPC(pRD));
m_walkingInterpreterFrames = m_crawl.isFrameless;
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